The present invention relates to a dispenser having an actuation indicator for indicating the number of actuations thereof. In particular, the invention relates to metered dose inhalers by means of which medicaments contained in an aerosol container may be administered to a patient.
It is well known to treat patients with medicaments contained in an aerosol, for example, in bronchoditator therapy. It is also known to use for such therapy, medicaments which are contained in an aerosol and are administered to a patient by means of an inhalation device comprising a tubular housing or sleeve in which the aerosol container is located and an outlet tube leading out of the tubular housing. The aerosol containers used in such inhalation devices are designed to deliver a predetermined dose of medicament upon each actuation by means of an outlet valve member at one end which can be opened either by depressing the valve member while the container is held stationary or by depressing the container while the valve member is held stationary. In the use of such devices, the aerosol container is placed in the tubular housing with the outlet valve member of the container communicating via a support with the outlet tube, for example a nozzle or mouthpiece. When used for dispensing medicaments, for example in bronchodilation therapy, the housing is then held by the patient in a more or less upright condition and the mouthpiece or nozzle of the inhalation device is placed in the mouth or nose of the patient. The aerosol container is pressed towards the support to dispense a dose of medicament from the container which is then inhaled by the patient.
A disadvantage arising from use of such known devices is that the patient cannot determine the amount of medicament in the container at any given time. In an extreme case this could mean that the patient, possibly suffering from severe bronchospasm and needing a dose of medicament, will find that the container will not dispense a dose because its contents have already been exhausted.
U.S. Pat. No. 4,817,822 describes an aerosol dispenser of the type described above having a dose indicating device which, in a first embodiment is removably attached to the end of the protruding portion of the aerosol container. The operating mechanism of the dose counter is located within a housing which extends from the end of the aerosol container along the external surface of the tubular housing. It is important with inhalation devices containing medicament that the contents of the aerosol container are clearly marked to ensure that the patient knows exactly what medication is contained. One disadvantage associated with this positioning of the dose indicating device is that the device obscures at least a part of the aerosol container and housing which creates labelling difficulties.
A further disadvantage of the device described is that if the dose indicating device is removably attached to the aerosol container, it is possible that the dose indicating device may become separated from its aerosol container with the result that the aerosol dispenser could be used without the dose indicating device, or the actuating mechanism of the indicating device could be tampered with leading to a false reading when the indicating device is re-attached to the dispenser. With patients having several different inhalers, it could even result in the indicating device being re-attached to the wrong dispenser.
In a second embodiment described in U.S. Pat. No. 4,817,822 the operating mechanism of the dose indicating device is located within a compartment in the housing and is actuated by means of an actuator member attached to the aerosol container. In this embodiment, once the aerosol container is fitted into the housing it cannot be removed. This makes cleaning of the housing very difficult. Even if the container were removable, the operating mechanism of the dose indicating device would be vulnerable to damage when washing with water, soap, disinfectant or antiseptic solutions. This is important because sprays of many aerosol formulations leave residues which can entrap dust and dirt particles. Some provide a media for the growth of undesired micro-organisms. If the growth of these micro-organisms is unchecked, they can serve as a source of infection for the patient and will often introduce pathogens into the patient""s respiratory tract.
WO96/16686 describes an aerosol dispenser wherein the operating mechanism of the dose indicating device is electronic and wherein the actuating member comprises a microswitch set into the wall of the housing. The electronic counting mechanism and microswitch are contained within a hermetically sealed enclosure. However, electronic assemblies of this type are relatively expensive compared to equivalent mechanical mechanisms, typically costing five or six times as much to produce depending on quantities manufactured. Such expense must ultimately be borne by the customer and may be prohibitive.
U.S. Pat. No. 5,482,030 describes an aerosol dispenser having a mechanical dose indicator device located in and connected to the housing in the vicinity of the outlet tube of the aerosol container when fitted. Its mechanical construction makes it difficult to seal against moisture ingress and so this dispenser again is difficult to wash without damaging the operating mechanism of the dose indicating device.
Many different pharmaceutical products are sold in the form of aerosol containers as discussed above, requiring different sized container bodies and/or valves according to the required specifications. It is therefore normal for there to be dimensional variations between different aerosol containers. Even between the same products there can be dimensional variations due to manufacturing tolerances. One problem which is common to all of the dose indicating devices discussed above is that the indicator mechanism, which is actuated by means of a switch which detects relative movement between the container body and housing, lacks any means of compensating for dimensional variations between different aerosol containers. Hence, the indicators described must be dimensioned according to the product with which they are to be used, and so will not be interchangeable with other products. Furthermore, in order for the dose indicators to work properly, the dimensions of the indicator, aerosol container and housing must be accurate.
It is an object to provide a dispenser having an actuation indicator which overcomes at least some of the above described disadvantages. It is a further object to provide such a dispenser which from the point of view of the patient closely resembles currently marketed dispensers in both external appearance and operation.
According to one aspect of the present invention there is provided a dispenser for dispensing medicament comprising a housing having a support; a container, locatable within said housing, having an outlet member, wherein said container is movable relative to the housing to enable dispensing therefrom and said outlet member is connectable with said support to prevent relative movement therebetween; and an actuation indicator, locatable within said housing, wherein the container and dose indicator are reversably removable from the housing as a single unit.
Suitably, the actuation indicator is engagable with the container in the vicinity of the outlet member. More preferably, the actuation indicator is engagable with the outlet member.
Suitably, the actuation indicator is provided with a grip member which is engagable with a neck portion of the container. Preferably, the neck portion is adjacent to or on the outlet member.
Suitably, the container is an aerosol container.
Suitably, the housing is provided with an outlet, more preferably in the form of a mouthpiece. Preferably, the dispenser comprises a passage through which dispensed doses may pass from the container to the outlet.
Suitably, the container provides measured doses.
Suitably, the actuation indicator indicates the number of doses dispensed from or remaining in the container.
Suitably, the actuation indicator comprises an indexing mechanism actuated by a predetermined movement of the aerosol container relative to the housing.
Preferably, the indexing mechanism comprises a lost motion coupling to allow and compensate for excess movement (xe2x80x98overtravelxe2x80x99) of the aerosol container relative to the housing.
By use of a lost motion coupling it is possible to create an actuation indicator of one size which can accomodate valves and actuators made within a wide range of manufacturing tolerances and can even fit a range of dispensers made to different dimensions.
Suitably, the indexing mechanism indexes the actuation indicator by means of a predetermined rotary movement of a first member driven by movement relative to a second member during actuation of the aerosol dispenser.
Suitably, the second member remains stationary relative to the housing during actuation of the aerosol dispenser.
Suitably, the first member comprises a pinion carried by a shaft through the lost motion coupling and the second member comprises a rack. Alternatively, the first member comprises a yoke and the second member comprises a post engaged by the yoke through the lost motion coupling.
Preferably, the lost motion coupling comprises a friction drive mechanism.
Suitably, the dispenser is a breath operated inhaler which is actuable in response to the inward breath of a user.
According to a particularly preferred aspect of the present invention there is provided an aerosol dispenser comprising a housing in which a container is removably located, an outlet leading from the housing and a support in the housing arranged to receive an outlet member of the container and having a passage through which the contents of the container may pass to the outlet, the outlet member being held stationary in the housing support and the body of the container being moveable relative to the outlet and housing to dispense its contents in measured doses, and a dose indicating device having a dose indicator for indicating the number of doses dispensed from or remaining in the container, characterised in that the dose indicating device is tightly connected to the container in the vicinity of the outlet member, such that the container and dose indicating device may be removed from the housing as a single unit.
According to a further aspect of the present invention there is provided an actuation indicating device for use with a dispenser comprising a housing and a container, locatable within said housing, having an outlet member, the actuation indicating device comprising attachment means to enable attachment to the container.
Suitably, the attachment means comprises a grip member which firmly engages a neck portion formed around the container. More preferably, the neck portion is located at the connection between the container and outlet member.
According to a particularly preferred aspect of the present invention the actuation indicating device has an actuation indicator for indicating the number of doses dispensed from or remaining in the container, wherein the actuation indicating device comprises attachment means to enable tight connection to the container in the vicinity of the outlet member.
By fixing the actuation indicating device to the container in the vicinity of the outlet member may be possible to make use of the physical dimensions of the crimped ferrule of standard containers to provide a tight snap fit between the dose indicating device and aerosol container for easy assembly yet which once assembled cannot be easily separated. This ensures that the actuation indicator presents accurate information concerning the container with which it is assembled.
In a preferred aspect, the dispenser is a metered dose inhaler comprising a housing in which the container is removably located, an outlet leading from the housing, a support in the housing arranged to receive the outlet member of the container and having a passage through which the contents of the container may pass to the outlet, the outlet member being held stationary in the housing support and the body of the container being moveable relative to the outlet and housing to dispense its contents in measured doses, and a window through which the dose indicator may be viewed.
The location of the dose indicator in the vicinity of the outlet member of the container in a metered dose inhaler provides the advantage that visually and operationally the device may appear very similar to current marketed metered dose inhalers without dose indicating devices such that when switched to the metered dose inhaler according to the invention, patients perceive little change over their conventional dispensers, so creating minimal impact upon patients and their use of the device.